Collimation Optimisation Frank Jackson, ILC BDS meeting, SLAC Jan 10, 2006

Collimation Performance BDS (20,15,2mrad) decks all rely on post-NLC ‘survivable spoiler’ optics Collimation phase advances and lattice bandwidth not been optimised yet Good simulated performance relies on tight energy spoiler settings, combined with more aggressive absorber apertures

NLC FD Bandwidth Exact phases and well behaved beta functions at FD

ILC 20 mrad lattice Non-exact phase advances (esp in vertical) x =2.76 y =2.34 Non-exact phase advances (esp in vertical) Poorer bandwidth

ILC-FF9 Collimation Optimisation x =2.75 y =2.75 Restore phase advances with matching section Bandwidth worsens Not only exact phase solution

Optimisation Strategy Tricky balance of phase and bandwidth variation Goal is to search the space of solutions for optimum Complement with spoiler/absorber aperture variation, tracking simulations

ILC-FF9 x =2.99 y =2.99

ILC-FF9 x =2.51 y =2.51